Method and apparatus for introducing steam and oxygen into a bath of molten steel



Aug. 30, 1966 J BELKm 3,269,829

METHOD AND APPARATUS FOR INTRODUCING STEAM AND OXYGEN INTO A BATH OF MOLTEN STEEL Filed Sept. 24, 1963 1L1; WM A nws/vron JACOB BEL/(IN .4 Homer United States Patent METHOD AND APPARATUS FOR INTRODUCING STEAM AND OXYGEN INTO A BATH OF MOLTEN STEEL Jacob Belkin, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Sept. 24, 1963, Ser. No. 311,177 4 Claims. (Cl. 75-60) This invention relates to apparatus for introducing steam and oxygen into a bath of molten metal and more particularly to the introduction of these materials into molten steel in an open hearth or other steel producing furnaces. The use of steam or water with the oxygen stream has been recommended as a method of suppressing the formation of brown fume that generally occurs when top blowing liquid metal with oxygen. The oxygen is generally supplied through a water cooled pipe or lance positioned with its discharge end immediately above the bath or slightly submerged in the bath. When steam or water is also introduced it is added to the oxygen stream or blown into the metal from a separate pipe contained in the same water cooled lance. This has the disadvantages that the lance must be at least double walled to permit passage of the cooling water between the pipe carrying the oxygen and the outer shell of the lance, separate piping is required for the cooling water and also for either the steam or water to be blown into the metal, and the heat content of the cooling Water is not used in the steel making process.

It is therefore an object of my invention to provide apparatus for introducing steam and oxygen into a bath of molten metal wherein separate cooling water is not required.

Another object is to provide such apparatus wherein the heat content of the water used in cooling the apparatus is returned to the molten metal.

Still another object is to provide a method of introducing steam and oxygen into a bath of molten metal wherein the cooling water is added to the oxygen for blowing into the metal.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

The single figure is a schematic view of the apparatus of my invention.

Referring more particularly to the drawings, reference numeral 2 indicates a bath of molten steel located in a furnace 4. A lance 6 is located above the bath 2 with its lower or forward end positioned either slightly above the top of the bath 2 as shown or slightly beneath the surface thereof. The lance 6 includes an inner tube 8 having holes 10 through the wall thereof which are spaced apart radially and circumferentially along the length of the tube. A tube 12 surrounds the tube 8 and has an inner diameter larger than the outer diameter of the tube 8 so as to provide a passageway 14. A plate 16 is welded to the forward end of tube 12 so as to completely close the end of tube 8 and to partially close the end of tube 12. Holes or orifices 18 are provided through the plate 16 in communication with the passageway 14. An outlet 20 is provided adjacent the rearward end of tube 8 and is connected to a flexible conduit 22. An outlet 24 is provided at the rearward end of tube 12 and is connected to a flexible conduit 26. Conduit 22 is connected to a water source, not shown,

3,269,829 Patented August 3.0, 1966 and conduit 26 is connected to an oxygen source, not shown.

In operation, the water in the tube 8 passes through the holes 10 into the oxygen stream in passageway 14. It will be seen that the holes 10 are spaced uniformly along the length of the tube 8 with the diameter of the holes 10 increasing in size from the rearward to the forward end of the tube 8 so that the water is distributed equally along the length of the passageway 14. The Water mixes with the oxygen stream in the passageway 14 and the heat absorbed by the pipe 12 from the furnace walls and the gases in the furnace will cause most of the water to vaporize. The water flow is adjusted so that the heat content of the steam is sufficient to absorb enough heat to keep the outside surface temperature of tube 12 at a safe level. The steam mixed with the oxygen passes through the holes 18 into the metal bath 2.

Assuming a lance having a 3 /2 in. outside diameter and an inner tube 8 having an inside diameter of 1.049 in. (nominal one in. pipe) experiments have shown that the total heat that must be removed to keep the lance at a safe temperature is 2.08 10 B.t.u. per hr. Assuming the heat of vaporization to be 1,000 B.t.u. per lb. the water requirements would be 2,080 lbs. per hr. and the water velocity would be 1.55 ft. per second. If 25,000 standard cu. ft. of oxygen were supplied per hr. the ratio of the weight of vaporized water blown into the metal to the weight of oxygen would be just under one. Assuming that of the water is disassociated into hydrogen and oxygen when it contacts the metal approximately 20,000 standard cu. ft. per hr. of additional oxygen would be supplied by the disassociation. Thus it is seen that there is approximately an increase in the oxygen supply and that 2x10 B.t.u. per hr. which would ordinarily be lost with a water cooled lance will be returned to the system by the practice of my invention.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. Apparatus for introducing steam and oxygen into a bath of molten metal comprising a first tube, means closing the forward end of said first tube, a second tube having an inner diameter greater than the outer diameter of said first tube surrounding said first tube and providing a passageway therearound, said first tube having longitudinally spaced holes in the wall thereof, means for introducing water into said first tube at the rearward end thereof, means closing the forward end of said second tube, said last named means having holes therein communicating with said passageway, and means for introducing oxygen into said second tube at the rearward end thereof.

2. Apparatus for introducing steam and oxygen into a bath of molten steel comprising a first tube, means closing the forward end of said first tube, a second tube having an inner diameter greater than the outer diameter of said first tube surrounding said first tube and providing a passageway therearound, said first tube having holes in the wall thereof spaced apart longitudinally and circumferentially throughout its length, the area of said holes per unit of length of said first tube increasing from the rearward to forward end thereof, means for introducing water into said first tube at the rearward end thereof, means closing the forward end of said second tube, said last named means having holes therein communicating with said second passageway and means for introducing oxygen into said second tube at the rearward end thereof.

3. Apparatus according to claim 2 in which the holes in said first tube are spaced uniformly along the length thereof with the size of said holes increasing from the rearward to forward end.

4. A method of introducing steam and oxygen into a bath of molten metal which comprises providing a lance having a first tube, means closing the forward end of said first tube, a second tube having an inner diameter greater than the outer diameter of said first tube surrounding said first tube and providing a passageway therearound, said first tube having holes in the wall thereof spaced apart radially and circumferentially throughout its length and means closing the forward end of said second tube, said last named means having holes therein communicating with said passageway, introducing water into said first tube adjacent its rearward end, introducing oxygen into said second tube adjacent its rearward end, and regulating the flow of water so that it will absorb sufficient heat from the second tube to maintain it at a safe temperature.

No references cited.

BENJAMIN HENKIN, Primary Examiner. 

4. A METHOD OF INTRODUCING STEAM AND OXYGEN INTO A BATH OF MOLTEN METAL WHICH COMPRISES PROVIDING A LANCE HAVING A FIRST TUBE, MEANS CLOSING THE FORWARD END OF SAID FIRST TUBE, A SECOND TUBE HAVING AN INNER DIAMETER GREATER THAN THE OUTER DIAMETER OF SAID FIRST TUBE SURROUNDING SAID FIRST TUBE AND PROVIDING A PASSAGEWAY THEREAROUND, SAID FIRST TUBE HAVING HOLES IN THE WALL THEREOF SPACED APART RADIALLY AND CIRCUMFERENTIALLY THROUGHOUT ITS LENGTH AND MEANS CLOSING THE FORWARD END OF SAID SECOND TUBE, SAID ;AST NAMED MEANS HAVING HOLES THEREIN COMMUNICATING WITH SAID PASSAGEWAY, INTODUCING WATER INTO SAID FIRST TUBE ADJACENT ITS REARWARD END, INTODUCING OXYGEN INTO SAID SECOND TUBE ADJACENT ITS REARWARD END, AND REGULATING THE FLOW OF WATER SO THAT IT WILL ABSORB SUFFICIENT HEAT FROM THE SECOND TUBE TO MAINTAIN IT AT A SAFE TEMPERATURE. 